Sex reversal (studies with various treatments- hormones, temperature variation, population crowding by female or male sex) and assessment of possible spontaneous sex reversal on several fish spp. which had been reported previously by several authors is being continued. The cases reported on sex reversal in several coral fishes may be due to the fact that hermaphroditism is prevalent among coral fish spp. 2. Analysis of clonal hyperdiploid CD 5+B cells in mice with Dr. E. Raveche. Studies were designed to investigate the growth requirements for a transplantable line of hyperdiploid CD 5+B cells. The clonal CD 5+B cells are derived from NZB mice and may be responsible for the autoantibody production observed in these mice. The hyperdiploid CD 5+B cells are not only a model for such autoimmune diseases as rheumatoid arthritis-and Sjogren's syndrome, they are very similar to the malignant cell in virtually all chronic lymphocytic leukemias. In all of these states, immunosuppression of normal B cell function is observed. Thus, a study of the hyperdiploid CD 5+B cells in NAB mice will help to dissect the growth requirements of CD 5+B cells in the human situation. 3. Kinetics of hemophoetic cell studies with Dr. G. Brecher. Enzymatic markers have replaced cytogenetic identification of sex matched donor cells. It seems that in addition to the T cell involvement, stromal incompatibilities between male and female syngeneic donors and hosts may be involved. 4. Post and prenatal diagnosis of karyotypic aberration studies and the genomic diagnosis of hemophilia A by R.F.L.P. analysis are being continued.